Method of reducing surfactant damage using compositions comprising benefit agents of defined high polarity

ABSTRACT

The invention provides a method of reducing surfactant damage in compositions comprising at least one surfactant and at least one benefit agent. The reduction in damage is measurable by decrease in number of protein binding sites in presence versus absence of benefit agent, or when benefit agent has solubility outside a defined range. The invention further relates to compositions comprising said surfactants and benefit agent(s) having reduced surfactant damage.

FIELD OF THE INVENTION

The present invention relates to a method of significantly reducingsurfactant damage (e.g., to skin or other protein-containing substrate)by utilizing compositions comprising benefit agents (e.g., oils,solvents) within a defined high polarity window (wherein polarity ismeasured using “Hansen Solubility Parameter” of the benefit agent). Theinvention further relates to compositions, particularly compositionseffective in reducing skin/protein damage, comprising benefitagents/oils falling within the defined polarity window. In anotherembodiment, the invention relates to a method of selecting benefitagents/oils or a class of benefit agents/oils which are best suited forreducing surfactant damage in surfactant containing compositions usingknowledge of Hansen solubility.

BRIEF SUMMARY OF THE INVENTION

It is well known that surfactant/cleanser can be harsh and damaging tothe skin. Generally, it is believed this occurs at least in part,because surfactant binds to proteins found in the skin and therebyinterferes with the role of the protein (e.g., in maintaining healthyskin).

It is also well known to utilize personal care compositions comprisingbenefit agents, such as oils. Oils are thought to provide an occlusionbarrier and to help alleviate skin dryness by, for example, reducingwater loss from the skin barrier.

Unexpectedly, applicants have now found that use of benefit agent insurfactant containing personal care compositions (e.g., personal careliquids, bars, etc.), particularly benefit agent falling within specificpolarity parameters (i.e., the polarity of the benefit agent orcombination of benefit agents), leads to reduced damage ofskin/substrate normally caused by the surfactant in such compositions.While not wishing to be bound by theory, it is believed that benefitagents falling within the defined polarity profiles act to inhibit theprocess of protein denaturing by interacting with the protein, therebyeffectively blocking the binding site on the protein molecule that isavailable for surfactant binding. It is this binding of surfactant toprotein which is believed largely responsible for the harmful impact ofsurfactant on skin.

In one embodiment, the invention further relates to a method ofselecting benefit agents/oils suitable for reducing surfactant damageusing knowledge of Hansen solubility parameters.

The following references are noted: U.S. Pat. No. 6,699,824 to Dawson etal.; EP 1 051 468 (assigned to Unilever); U.S. Pat. No. 6,380,150 toToussaint et al.; JP 2004/203848 (assigned to Lion Corp); EP 0 912 666(assigned to Colgate); and WO 96/37594 (assigned to P&G).

None of the noted references teaches or suggests a method of reducingsurfactant damage to skin or other substrate using benefit agents (e.g.,oils, solvents) having a defined polarity or a method of selectingbenefit agents or a class of benefit agents suitable for reducing suchdamage.

BRIEF DESCRIPTION OF THE INVENTION

In one embodiment, the present invention relates to a method of reducingsurfactant damage (e.g., reducing surfactant binding to skin proteins)which comprises using surfactant-containing compositions (preferably,but not necessarily, liquid compositions) comprising benefit agent orcombination of benefit agents having high polarity (within a definedpolarity window). The polarity of a benefit agent can in turn beexpressed as a function of the Hansen solubility parameter of thebenefit agent.

In a preferred embodiment of the first embodiment, the invention relatesto a method of reducing surfactant damage in a composition comprisingsurfactant or surfactants, preferably comprising at least one anionicsurfactant (generally anionic surfactants are harsher than othersurfactants on skin), wherein said method comprises using, in additionto the surfactant or surfactants, a benefit agent(s) with Hansensolubility parameter between about 16.5 and 37 (see examples),preferably 17 and 30, more preferably between 19 and 27.

In a second embodiment of the invention, the invention comprises amethod of selecting benefit agent to be used to reduce surfactant damagein a composition comprising at least one surfactant and benefit agent,wherein said process comprises (1) determining Hansen solubilityparameters (HSP) of the benefit agent (e.g., by calculating the HSPusing molecular modeling software, such as ChemSW (version 3.33), whichuses an empirical group contribution model to calculate HSP based onknown chemical structure); and (2) selecting said benefit agent(s)having HSP of between 16.5 and 37 alone or in combination, preferablyhaving HSP of between 17 and 30, more preferably 19 and 27.

In a third embodiment, the invention relates to compositions comprisingsurfactant and a benefit agent or combination of benefit agents havingHSP from 16.5 to 37. Such composition has reduced surfactant damage(e.g., at least 5% fewer binding sites) relative to composition withsame type and amount of surfactant(s) comprising benefit agent(s) havingHSP below 16.5 or above 37 or having no benefit agent.

These and other aspects, features and advantages will become apparent tothose of ordinary skill in the art from a reading of the followingdetailed description and the appended claims. For the avoidance ofdoubt, any feature of one aspect of the present invention may beutilized in any other aspect of the invention. It is noted that theexamples given in the description below are intended to clarify theinvention and are not intended to limit the invention to those examplesper se. Other than in the experimental examples, or where otherwiseindicated, all numbers expressing quantities of ingredients or reactionconditions used herein are to be understood as modified in all instancesby the term “about”. Similarly, all percentages are weight/weightpercentages of the total composition unless otherwise indicated.Numerical ranges expressed in the format “from x to y” are understood toinclude x and y. When for a specific feature multiple preferred rangesare described in the format “from x to y”, it is understood that allranges combining the different endpoints are also contemplated. Wherethe term “comprising” is used in the specification or claims, it is notintended to exclude any terms, steps or features not specificallyrecited. All temperatures are in degrees Celsius (° C.) unless specifiedotherwise. All measurements are in SI units unless specified otherwise.All documents cited are—in relevant part—incorporated herein byreference.

BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 is a graph of surfactant deposition (i.e., deposition of anionicsurfactant sodium dodecyl sulfate, or SDS), measured in micrograms/cm²(analyzed by HPLC method) when measured alone and when measured withvarious benefit agents (oils, solvents, etc.). As noted, when measuredin combination with triolein, a high polarity oil having an HSP withinthe range defined by the invention (HSP of 23.77) deposition decreases.This is a signal of less surfactant binding. By contrast, when measuredin combination with dodecane (relatively non-polar oil of HSP 16.02),deposition was about the same or higher (more binding).

FIG. 2 is a measure of the b* value (defined in protocol). The figureshows that combination of SDS plus triolein (versus SDS plus dodecane orSDS alone) have smaller b* value, which again is indicative of lesssurfactant binding (associated with less damage).

FIG. 3 shows that, as more oil is used, the oil induces aggregation ofprotein. While not wishing to be bound by theory, protein aggregation isbelieved to be one of mechanisms by which benefit agent of high polarity(defined by HSP of 16.5 to 37, preferably 17 to 30) protects protein(e.g., from being “attacked” by surfactant(s))

FIG. 4 shows that, as amount of benefit agent is increased, the amountof heat that is needed to denature protein used in combination with thebenefit agent is increased. Again, while not wishing to be bound bytheory, protection from denaturation is believed to be another mechanismby which benefit agent protects protein from attack by surfactant(s).

FIG. 5 shows that, without benefit agent of higher polarity (defined byHSP), protein will be denatured by surfactant at much lower temperaturethan if benefit agent is used.

FIG. 6 shows the correlation between the in-vitro surfactant binding toprotein and in-vivo skin irritation. As more molecules are binded (e.g.,because of HSP outside defined optimal window), mean irritationincreases.

DETAILED DESCRIPTION OF THE INVENTION

The present invention relates to the fundamental observation that, whena surfactant system which normally causes damage to skin or othersubstrate (e.g., by causing denaturing of protein) is used incombination with benefit agent or agents of a defined polarity, thesurfactant damage (measured by the number of surfactant molecularbinding sites binded per protein molecule) caused by the surfactant canbe reduced.

In one embodiment of the invention, the invention relates to a method ofreducing surfactant damage (measurable, for example, by reduction innumber of surfactant binding per protein molecule) of at least about 5%compared to number of sites binded using surfactant(s) and no benefitagent or benefit agent outside polarity window, wherein said methodcomprises, in compositions comprising at least one surfactant and atleast one benefit agent, selecting a benefit agent or combination ofbenefit agents having high polarity. Polarity of benefit agents so usedcan be expressed as a function of the HSP. In another embodiment, theinvention relates to a method of selecting benefit agent(s) suitable forreducing the surfactant damage.

Surfactant

Preferably, although not necessarily, the at least one surfactant shouldbe an anionic surfactant and, if a mixture of surfactants is used, atleast one of said mixture should be an anionic surfactant.

Surfactant(s), when used in a fully formulated composition, may comprisefrom 2% to 90% of the composition, depending on whether the surfactantsare formulated as part of a bar composition, liquid composition, cream,etc.

For example, if part of a rinse-off liquid cleanser composition,surfactant or surfactants may comprise 2 to 75% of a surfactant selectedfrom the group consisting of anionic, nonionic, amphoteric/zwitterionic,cationic surfactant and mixtures thereof.

Among suitable anionic actives which may be used are the alkyl ethersulfates, acyl isethionates, alkyl ether sulfonates, sarcosinates,sulfosuccinates, taurates and combinations thereof. Among suitableamphoteric actives may be included alkylbetaines, amidopropyl betaines,amidopropyl sultaines and combinations thereof.

Alkyl ether sulfates of the present invention may be of the generalformulaR—(OCH₂CH₂)_(n)OSO₃-M⁺

wherein R ranges from C₈-C₂₀ alkyl, preferably C₁₂-C₁₅ alkyl, n is aninteger from 1 to 40, preferably from 2 to 9, optimally about 3, and M⁺is a sodium, potassium, ammonium or triethanolammonium cation.

Typical commercial co-actives of this variety are listed in the Tablebelow: Physical Trademark Chemical Name Form Manufacturer Steol CS 330Sodium Laureth Sulfate Liquid Stepan Standopol ES-3 Sodium LaurethSulfate Liquid Henkel Alkasurf ES-60 Sodium Laureth Sulfate PasteAlkaril Cycloryl TD TEA Laureth Sulfate Paste Cyclo Standopol 125-ESodium Laureth-12 Sulfate Liquid Henkel Cedepal Sodium Trideceth SulfatePaste Miranol TD407MF Standopol EA-2 Ammonium Laureth Sulfate LiquidHenkel

Alkyl ether sulfonates may also be employed for the present invention.Illustrative of this category is a commercial product known as AvenelS-150 commonly known as a sodium C₁₂-C₁₅ Pareth-15 sulfonate.

Another active type suitable for use in the present invention is that ofthe sulfosuccinates. This category is best represented by the monoalkylsulfosuccinates having the formula R₂OCCH₂CH(SO₃XNa⁺)COOXM⁺; andamido-MEA sulfosuccinates of the formula:RCONHCH₂CH₂O₂CCH₂CH(SO₃XM⁺)COOXM⁺; wherein R ranges from C₈-C₂₀ alkyl,preferably C₁₂-C₁₅ alkyl and M⁺ is a sodium, potassium, ammonium ortriethanolammonium cation. Typical commercial products representative ofthese co-actives are those listed in the Table below: Physical TrademarkChemical Name Form Manufacturer Emcol 4400-1 Disodium Lauryl Solid WitcoSulfosuccinate Witco C5690 Disodium Cocoamido MEA Liquid WitcoSulfosuccinate McIntyre Disodium Cocoamido MEA Liquid McIntyre MackanateSulfosuccinate CM40F Schercopol Disodium Cocoamido MEA Liquid ScherCMSNa Sulfosuccinate Emcol 4100M Disodium Myristamido MEA Paste WitcoSulfosuccinate Schercopol Disodium Oleamido MEA Liquid Scher VarsulfS13333 Disodium Ricionoleamido Solid Scherex MEA Sulfosuccinate

Sarcosinates may also be useful in the present invention as a co-active.This category is indicated by the general formula RCON(CH₃)CH₂CO₂XM⁺,wherein R ranges from C₈-C₂₀ alkyl, preferably C₁₂-C₁₅ alkyl and M⁺ is asodium, potassium ammonium or triethanolammonium cation. Typicalcommercial products representative of these co-actives are those listedin the Table below: Physical Trademark Chemical Name Form ManufacturerHamposyl L-95 Sodium Lauroyl Sarcosinate Solid W. R. Grace Hamposyl TEACocoyl/Sarcosinate Liquid W. R. Grace TOC-30

Taurates may also be employed in the present invention as co-actives.These materials are generally identified by the formulaRCONR′CH₂CH₂SO₃XM⁺, wherein R ranges from C₈-C₂₀ alkyl, preferablyC₁₂-C₁₅ alkyl, R′ ranges from C₁-C₄ alkyl, and M⁺ is a sodium,potassium, ammonium or triethanolammonium cation. Typical commercialproducts representative of these co-actives are those listed in theTable below: Physical Trademark Chemical Name Form Manufacturer IgeponSodium Methyl Cocoyl Taurate Paste GAF TC 42 Igepon T-77 Sodium MethylOleoyl Taurate Paste GAF

Within the category of amphoterics there are three general categoriessuitable for the present invention. These include alkylbetaines of theformulaRN⁺(CH₃)₂CH₂CO₂XM⁺,

amidopropyl betaines of the formula RCONHCH₂CH₂CH₂N⁺(CH₃)₂CH₂CO₂XM⁺, andamidopropyl sultaines of the formula RCONHCH₂CH₂N⁺(CH₃)₂CH₂SO₃XM⁺wherein R ranges from C₈-C₂₀ alkyl, preferably C₁₂-C₁₅ alkyl, and M⁺ isa sodium, potassium, ammonium or triethanolammonium cation. Typicalcommercial products representative of these co-actives are found in theTable below: Physical Trademark Chemical Name Form ManufacturerTegobetaine F Cocamidopropyl Betaine Liquid Goldschmidt Lonzaine CCocamidopropyl Betaine Liquid Lonza Lonzaine CS Cocamidopropyl LiquidLonza Hydroxysultaine Lonzaine 12C Coco-Betaine Liquid LonzaSchercotaine MAB Myristamidopropyl Liquid Lonza Betaine Velvetex OLB-50Oleyl Betaine Paste Henkel

Within the broad category of liquid actives, the most effective are thealkyl sulfates, alkyl ether sulfates, alkyl ether sulfonates,sulfosuccinates, and amidopropyl betaines.

Another preferred surfactant is an acyl isethionate having the formula

in which R denotes a linear or branched alkyl group and M denotes analkali metal or alkaline earth metal or an amine.

Another surfactant which may be used are the monoalkyl ordialkylphosphate surfactants.

Another surfactant which may be used, preferably used as primarysurfactant in combination with other surfactants noted above, is sodiumcoco glyceryl ether sulfonate. While desirable to use because of itsmildness properties, this coco AGS alone does not provide optimum lathercreaminess. A sodium 90/10 coconut/tallow alkyl AGS distribution ispreferred for creaminess. Salts other than the sodium salt such as TEA-,ammonium, and K-AGS and chain length distributions other than 90/10coconut/tallow are usable at moderate levels. Also, some soap may beadded to improve lather volume and speed of lathering. Certain secondaryco-surfactants used in combination with AGS can also provide a creamierand more stable lather. These secondary surfactants should also beintrinsically mild. One secondary surfactant that has been found to beespecially desirable is sodium lauroyl sarcosinate (trade name HamposylL, made by Hampshire Chemical).

The amphoteric betaines and sultaines noted above can be used as thesole surfactant, but are more preferred as a co-surfactant. Nonionicsgenerally should not be used as the sole surfactant in this product ifhigh foaming is desirable; however, they can be incorporated as aco-surfactant.

Nonionic and cationic surfactants which may be used include any one ofthose described in U.S. Pat. No. 3,761,418 to Parran, Jr., herebyincorporated by reference into the subject application. Also includedare the aldobionamides as taught in U.S. Pat. No. 5,389,279 to Au et al;and the polyhydroxy fatty acid amides as taught in U.S. Pat. No.5,312,934 to Letton, both of which are incorporated by reference intothe subject application.

Soaps may also be used. The soaps may be added neat or made in situ viaadding a base, e.g., NaOH; to convert free fatty acids.

A preferred surfactant active system is one such that acyl isethionatecomprises 1 to 15% by weight of the total composition and/or an anionicother than acyl isethionate (e.g., ammonium lauryl ether sulfate)comprises 1 to 15% by weight of the total composition and amphotericcomprises 0.5 to 15% by weight of the total composition.

Another preferred active system is one comprising 1 to 20% alkyl ethersulfate. Preferred surfactant systems may also contain 1 to 10% alkalimetal lauryl sulfate or C₁₄-C₁₆ olefin sulphonate instead of acylisethionate.

Also, in the preferred embodiment, the Hansen solubility parameter ofthe benefit agent or benefits agents used in combination with thesurfactant system should be between 16.5 and 37, preferably 17 and 30,more preferably 19 and 27. When used in a fully formulated composition,the benefit agent(s) will generally comprise 0.1 to 50% by wt.,preferably 0.5 to 30%, more preferably 1 to 25% by wt. of the finalcompositions.

Hansen solubility parameter is the total energy of vaporization of aliquid. This total energies consists of several individual parts arisingfrom (atomic) dispersion forces, (molecular) permanent dipole-permanentdipole forces, and (molecular) hydrogen bonding (electron exchange). Thebasic equation which governs the assignment of Hansen parameters is thatthe total cohesion energy, E, must be the sum of the individual energieswhich make it up.E=E _(D) +E _(P) +E _(H)where E_(D), E_(P), E_(H) are the dispersion cohesion energy, polarcohesion energy and hydrogen bonding cohesion energy, respectively. TheHansen solubility parameter (δ, in unit MPa^(1/2)) is thus defined as:δ2=(E _(D) /V)+(E _(P) /V)+(E _(H) /V)=δ2_(D)+δ2_(P)+δ2_(H)where V is the molar volume, and δ_(D), δ_(P), δ_(H) are the Hansen D(dispersion cohesion energy), P (polar cohesion energy) and H (hydrogenbonding cohesion energy).

As noted, the benefit agent may be used in a fully formulatedcomposition in an amount from about, 0.1 to 50% by wt., depending onform of composition.

Examples of oil/solvent or oil/solvent systems having HSP with ranges ofinvention include alkyl lactate (e.g., butyl lactate), alkyl alcohols(e.g., octyl dodeconol), alcohol such as ethanol, butanol etc.

In a second embodiment of the invention, the invention comprises amethod of selecting oil(s)/solvent(s) to be used to reduce surfactantdamage in a composition comprising at least one surfactant and benefitagent, wherein said process comprises:

-   -   (1) determining Hansen solubility parameter of a benefit agent        (e.g., by testing or by finding in literature, and/or by using        molecular molding surfactant); and    -   (2) selecting said benefit agent(s) having a Hansen solubility        parameter of between 16.5 and 37, preferably 17 and 30, more        preferably 19 to 27.

Reduction in surfactant damage may be defined by reduction in number ofbinding sites binded by surfactant(s) to given protein whensurfactant(s) are used in combination with oil/solvent compared to wheresurfactant alone is used.

Specifically the reduction may be defined in reduction of sites bindedof at least about 5%, preferably at least about 10%, more preferably atleast about 10% to 50% (and preferably higher) relative to compositionwithout benefit agent or relative to composition with benefit agentoutside the defined polarity window.

In a third embodiment, the invention relates to compositions comprisingsurfactant and a benefit agent or combination of benefit agents havingsolubility parameter from 16.5 to 37; said composition have reducedsurfactant damage. Again, damage is measured by reduction in sites onsurfactant binded of at least 5%, preferably at least 10% relative tocomposition with same surfactant type and amount comprising benefitagent(s) with HSP below 16.5 or above 37, or relative to compositionwith same type and amount of surfactant and no benefit agent.

Definitions

-   -   SDS=Sodium dodecyl sulfate    -   SLES=Sodium lauryl ether sulfate    -   CAPB=Cocoamidopropybetaine    -   CETIOL OE=Dicaprylyl ether    -   IPM=Isopropylmyristate    -   Castor oil 318 (also known as Surfactol® 318 from CasChem, Inc.        in Bayonne, N.J.) is ethoxylated castor oil with on average 5        PEG unit per castor oil molecule    -   Castor oil 365 (also known as Surfactol® 365 from CasChem, Inc.        in Bayonne, N.J.) is ethoxylated castor oil with on average 40        PEG unit per castor oil molecule    -   BSA=Bovine serum albumin    -   HPLC=High performance liquid chromatography    -   DSC=Differetial Scanning chromatography    -   B*=The Commission International de l'Eclairage (CIE) L*a*b*        color system is used an objective measurement parameter for        color. In the 3-dimensional space, L*(luminescence) represents        the grey level from black to white, a* represents the green-red        component and b* the blue-yellow component.        Methodology/Protocol        Conductivity Test:

Conductance measurements were carried out at room temperature by use ofa Thermo conductivity meter, model Orion 150+. Routinely, the titrationswere performed by adding a controlled amount of 10% of stock surfactantsolution under magnetic stirring into the 0.5% BSA (Bovine SerumAlbumin) in 0.02M acetate buffer at pH˜5.2. Values of CMC (criticalmicellization concentration), CAC (critical aggregation concentration)and protein saturation point (PSP) were defined by the changing of theslope of the conductivity vs. surfactant concentration plots. The numberof surfactants binding to each protein can be calculated by:{[PSP]−[CAC]}/{[protein]/Mw_(protein)}, where [protein] is the proteinconcentration.

Indigo Carmine Surfactant/Dye Binding Procedure

A modification of the procedure described by Imokawa and Mishima(Contact Dermatitis 5:357-366, 1979) was used. Two mil of eachsurfactant sample were placed into plastic chambers resting on the volarforearm skin (area ˜3.14 cm²) for 2 minutes. The samples were removed,and the sites rinsed with 2 mls of deionized water. Two mil of 1% Indigocarmine dye were then added to each chamber for 1 minute and then thesites were rinsed with 2 mil of deionized water. The sites were patteddry with a paper towel. Digital images were obtained for each arm, andeach skin site was measured for its L*a*b* values using a Minolta CM508D. The Commission International de I'Eclairage (CIE) L*a*b* colorsystem is used an objective measurement parameter for color. In the3-dimensional space, L*(luminescence) represents the grey level fromblack to white, a* represents the green-red component and b* theblue-yellow component. In this study, each skin site was measured forits L*a*b* values using a Minolta CM 508D spectrophotometer.

The Minolta CM 508D takes three readings on each test site and reportsthe average. Three sets of average readings were obtained for each siteand the values averaged again.

HPLC Test for Surfactant Deposition:

8 weeks old white pig skin was shaved and washed in warm water. Ethanolsprayed and rinse/wiped with wipeall, and then stored it at −7° C. Dosecontrolled amount of surfactant sample (3.3 mg of per cm²) onto pig skinof known surfactant area. Rub for 30 sec. Let stand for 1.5 min. Andthen rinse for 10 sec under 100° F. running water. Pat dry and let theskin dry in the hood for around 10 min. Then perform 3 times 1 minextraction using 2 ml mixture solvent (25% chloroform/25% water/50%methanol, by volume) on pig skin for surfactant extraction. Evaporatesolvent under liquid N₂ and dissolve the content in the vial with 0.5 mlof mobile phase for HPLC analysis using ELSD 2000 detector.

Dynamic Light Scattering for Protein Size:

The size of protein molecule was measured by 90Plus/Bi-MAS multi angleparticle size, BrokeHaven. The scattering angle is 90° and thewavelength is 635 nm. 0.5% of protein in acetate buffer (pH=5.2,IS=0.02M) was used. The protein sample was filtered three times by asyringe filter with 0.1 μm pore size Nylon membrane prior to themeasurement. All experiments were carried out at room temperature (25°C.). The scattered field autocorrelation function (g(q, τ)) vs. delaytime (τ) was obtained from each measurement. A cumulant model was usedto fit the autocorrelation function with the delay time to calculate thesize of the protein.

Micro—DSC for Protein Denaturation:

1.2% of BSA acetate buffer solution was prepared (pH 5.2, IS 0.02). Anaccurately measured amount of sample solution was loaded in DSC samplechamber and the thermal behavior of the sample was studied over therange of 5 to 102° C. at a heating rate of 0.5° C./min. Then the BSAacetate solution was titrated with either oil, or surfactant, oroil/surfactant at 1:1 ratio. After each titration, a DSC measurement wasperformed.

14-Day Cumulative In Vivo Patch Test

A randomized, double-blind study was conducted and consisted of onecell, with 24 subjects 18-65 years of age. Patching occurred for 14consecutive days, except on Sundays. Patches applied on Saturday wereleft in place until Monday, when freshly prepared patches were applied.The designated patch test sites were approximately 2 cm×2 cm on theintrascapular area of the back, and approximately 0.2 ml of test productwas applied to each patch. Each day following application, the patcheswere removed, the sites evaluated for irritation, and identical patchesreapplied to the same test sites. Monday's irritation scores also wererecorded as Sunday's scores, with Sundays being counted as exposuredays. Individual test article scores were calculated via summation ofthe results for each day. Cumulative irritation scores were the sum ofthe numerical irritation grades assigned daily during the 14-day testperiod.

EXAMPLE 1-10 & COMPARATIVES A & B

In order to show the effect of benefit agent having different polarityon binding to protein molecule (a reflection of the harshness ofsurfactant; more surfactant binding to protein equal harsher and moredamage expected), applicants tested surfactant binding of (1) surfactantalone and (2) of surfactant in combination with various oils/cosolvents(at 1:1 surfactant to oil ratio) to see level of (how many) surfactantsbinding per protein molecule (e.g., BSA) at saturation. The tests weredone using conductivity test described in protocol and results are setforth below in Table 1. TABLE 1 Surfactant binding to BSA proteinmeasured by conductivity: 10% SDS with 10% oil compared to 10% SDSalone. Hansen solubility Saturated parameter of binding: No. ofoil/cosolvent surfactant per Example (MPa^(1/2)) BSA at saturation 10%SDS (surfactant alone) Control — 220 10% SDS + 10% butyl 1 19.58 169lactate 10% SDS + 10% octyl 2 16.98 189 dodecanol 10% SDS + 10% wickenol3 18.56 192 10% SDS + 10% cetiol OE 4 16.85 201 10% SDS + 10% IPM A16.02 237 10% SDS + 10% dodecane B 16.02 243 10% SDS + 10% triolein 523.77 172 10% SDS + 10% glycerin 6 36.46 202 10% SDS + 10% methanol 729.64 188 10% SDS + 10% ethanol 8 26.49 158 10% SDS + 10% butanol 923.28 141 10% SDS + 10% hexanol 10  21.11 99

As seen, in most cases the number of surfactants binded by BSA went downwhen oil solvent was added (since surfactant binding is associated withharshness, this is desirable).

On a molecular level, it can be noted that different oils/water solublesolvents have different effect on surfactant binding to protein. Thus,as seen from comparatives A & B (where the Hansen solubility of oiland/or cosolvent was about 16) there was little reduction in number ofsurfactants binding compared to control with no oil/cosolvent); withother oils/cosolvent there was a mild level of reduction; and with yetother oil/cosolvents (see Example 1 or 5) reduction was quitesignificant.

Applicants believe there is an optimized polarity window (defined byHansen solubility parameter of about 16.5 to 37, preferably 17 to 30,more preferably 19 to 27 where most significant reduction is found.

On a macro level, Examples 17-18 and 19 below show that, where polaroil/solvent reduce surfactant binding as measured on a molecular level,surfactant deposition onto skin after wash is also reduced. Therefore,there is a clear link between surfactant binding to protein molecule andsurfactant binding to skin during wash.

Further, in a patch test (see Example 23 and FIG. 6), there is a strongcorrelation between the irritation score and the surfactant binding toprotein in molecular level.

EXAMPLES 11-16

Applicants conducted same test as in Examples 1 to 10, but usedSLES/CAPB surfactant system instead of SDS. Results are set forth inTable 2 TABLE 2 Surfactant binding to BSA protein measured byconductivity: 10% SLES/CAPB (2:1) with 10% oil compared to 10% SLES/CAPB(2:1) alone Hansen Saturated solubility binding: No. of parameter ofsurfactant per oil/cosolvent, BSA at Example (MPa^(1/2)) saturation 10%SLES/CAPB (2:1) Control — 183 10% SLES/CAPB (2:1) + 11 19.58 95 10%butyl lactate 10% SLES/CAPB (2:1) + 12 16.98 97 10% octyl dodecanol 10%SLES/CAPB (2:1) + 13 18.56 145 10% wickenol 10% SLES/CAPB (2:1) + 1416.85 160 10% cetiol DE 10% SLES/CAPB (2:1) + C 16.02 165 10% IPM 10%SLES/CAPB (2:1) + D 16.02 192 10% dodecane 10% SLES/CAPB (2:1) + 1523.77 110 10% triolein 10% SLES/CAPB (2:1) + 16 36.46 150 10% glycerin

This example, similar to Examples 1-10, is showing that the effect ofbenefit agent(s) to reduce surfactant binding to protein is dependent onthe polarity of the benefit agent: the higher the polarity, the moreeffective to reduce surfactant binding to protein. There is a window ofsolubility parameter (from 16.5 to 37, or preferably from 17 to 30, morepreferably 19 to 27) that offers the most reduction on surfactantbinding to protein.

Importantly, it should be noted is that the choice of oil/solvent tomost efficiently reduce surfactant binding to protein is not dependenton surfactant type.

EXAMPLES 17-18

In order to further show the protective effect of benefit agent (e.g.,oil), applicants compared surfactant deposition onto skin after wash,using solvent extraction and HPLC method defined in protocol section,for 10% SDS alone and compared with 10% SDS used with dodecane; or usedwith triolein. Results are seen in FIG. 1 and the amount of SDSdeposition on skin after wash is also listed in Table 3 below: TABLE 3Surfactant Deposition Onto Pig Skin after Wash Examined by SolventExtraction After Skin Wash and HPIC SDS deposition on Example skin(μg/cm²) 10% SDS Control 17.6 10% SDS + 10% dodecane 17 15.9 10% SDS +10% triolein 18 11.9

From FIG. 1 and Table 3, it was found that pig skin washed with SDS hasthe highest amount of SDS surfactant deposited (17.6+/−1.2 μg/cm2); thatpig skin washed with SDS+dodecane (1:1 surfactant to oil ratio) hasslightly lower SDS surfactant deposition (15.9+/−0.5 μg/cm²); while pigskin washed with SDS+/31 triolein (1:1 surfactant to oil ratio) hassignificantly lower SDS surfactant deposition (11.9+/−0.5 μg/cm²). Notethat from the in-vitro surfactant binding to protein molecule data shownin Example 1, polar oil such as triolein leads to less surfactantbinding to protein on the molecular level than non-polar oil such asdodecane. Therefore, the in-vivo surfactant deposition data and thein-vitro surfactant-protein binding data agree with each other,indicating that polar oil such as triolein will lead to less surfactantbinding both on the micro-scale level (surfactant molecule binds toprotein molecule) and on the macro-scale level (surfactant binds to skinduring wash).

EXAMPLE 19

Applicants again ran a test using SDS versus SDS and dodecane versus SDSand triolein and results are set forth in FIG. 2. Here test measuredbinding to human forearm during washing (indigo carmine staining test toskin) and 0.5% of each of the three solutions was used to test. A lowerb* value indicates less surfactant binding on skin. As shown in FIG. 2,forearm washing with SDS+triolein (a polar oil) shows a lower b* valuethan SDS alone and SDS+dodecane (a non-polar oil), indicating lesssurfactant binding to skin after awash. This example once again showsthat polar benefit agent (e.g., oil) reduces surfactant binding betterthan non-polar benefit agent.

EXAMPLE 20

While not wishing to be bound by theory, applicants believe that onemechanism by which benefit agent protects surfactant from denaturation(and exposure to surfactant) is by inducing protein aggregation.

In this regard, applicants measured size of protein (using sunflowerseed oil and BSA protein) by dynamic light scattering techniquedescribed in protocol section to determine extent of oil induced proteinaggregation. As seen from FIG. 3, at roughly 1 to 5 ratio of benefitagent to protein, an increase in protein size was detected by dynamiclight scattering thereby indicating aggregation of protein.

EXAMPLE 21

Again, while not wishing to be bound by theory, applicants believebenefit agent (e.g., oil) helps stabilize protein from denaturation (andgreater exposure to surfactant) by increasing the heat needed todenature the protein.

In this regard, using DSC measurement technique described in methodologysection applicants determined that protein alone (BSA) has denaturationenthalpy of about 497 KJ/mol. As indicted in FIG. 4, addition oftriolein to the protein solution increases heat needed to achievedenaturation until it reaches a plateau at oil/protein ratio of 1 to 5.

EXAMPLE 22

Again, using DSC data (as shown in FIG. 5), applicants determined that,without benefit agent, SDS willfully denature BSA protein when at roomtemperature (indicated by denaturation enthalpy approaching zero) at aratio of about 1.2 to 1 surfactant to protein. However, when there is a1:1 mixture of SDS triolein, BSA protein is not fully denatured at roomtemperature until about ratio of 1.8 surfactant to protein. This dataclearly indicates that triolein is protecting BSA from surfactantdamage.

EXAMPLE 23

In FIG. 6, the in-vitro surfactant binding to protein data was comparedto in vivo skin irritation data (measured according to the “14-DayCumulative In vivo Patch Test” listed in protocol). As shown in FIG. 6,the in vivo data positively correlated with the in vitro findings(r²=0.887) that those polar oils (having higher levels of alkoxylated)lead to less surfactant binding to protein in-vivo also lead to lessirritation in-vivo.

1. A method of reducing surfactant damage in compositions comprising atleast one surfactant and at least one benefit agent wherein saidreduction is measurable by decrease in number of protein binding sitesbinded by surfactant when benefit agent is present compared to whenbenefit agent is absent, or compared to when benefit agent used hassolubility outside defined range, wherein said method comprisesselecting or using said benefit agent or agents having a benefit agentHansen solubility of 16.5 to 37
 2. A method according to claim 1,wherein said at least one surfactant is anionic surfactant.
 3. A methodaccording to claim 1, wherein benefit agent oil or agents has solubilityof 17 to
 30. 4. A composition comprising surfactant and benefit agent orcombination of benefit agent wherein said benefit agent or combinationof benefit agent has Hansen solubility of 16.5 to 37, wherein saidcomposition has reduced surfactant damage relative to composition withsame surfactant type and amount comprising benefit agent or combinationof benefit agents with Hansen solubility less than 16.5 or greater than37 or relative to composition with same surfactant type and amount andhaving no benefit agent.